Definition of
Gestational Diabetes Mellitus
The WHO has defined
Diabetes Mellitus as either a raised fasting blood glucose level of > 7.8
mmol/L or a level of > 11.0 mmol/L 2 hours following a 75 g oral glucose
load.
Pathogenesis of
Gestational Diabetes Mellitus
Fetal hyperinsulinemia
Effects of Fetal
Hyperinsulinemia
1. Reduced lung
surfactant à
Respiratory Distress Syndrome (RDS)
2. Increased
erythropoiesis can leads to jaundice or hyperviscosity syndrome. Hyperviscosity
syndrome will later develops into necrotizing colitis or renal vein thrombosis.
3. Increased fetal
metabolism which will increases O2 demand. Low O2 supply from the mother can
leads to intrauterine death.
4. Macrosomia à shoulder dystocia
5. Hypoglycaemia
6. Hypertrophic
myocardiopathy
Effects of Diabetes on
Pregnancy
1. Increased
miscarriage rate
2. Increased perinatal
loss due to intrauterine death (IUD)
3. Macrosomic baby
hence is at risk of dystocia
4. Fetal lung
maturation may be delayed; if the fetus was delivered prematurely, the risk of
getting RDS is increased
5. Risk of
preeclampsia
6. Risk of
polyhydramnios
7. Susceptible to
infections; mainly UTI and candida vaginitis
Management of Diabetes
A.
Pre pregnancy
The women who are known
to be diabetic and women who have had gestational diabetes should seek medical
attention before they get pregnant. This consultation offers opportunities in
explaining to them about;
1. The reason for
meticulously maintaining her blood glucose at normal level before conception
2. The need of taking
folic acid to reduce the risk of neural tube defects
This consultation can
also be used as an assessment for the presence of any complication related to
diabetes, such as diabetic retinopathy and nephropathy. Women who are on oral
hypoglycemic drugs should preferably be changed to insulin therapy. We should
check for her glycosylated Hemoglobin, HbA1c that reflects her glucose control
over the previous 10 weeks. High levels of HbA1c are associated with an increased
rate of fetal abnormality.
B. Pregnancy
Euglycemic state
should be maintained; with fasting glucose less than 5.3mmol/L and 2 hour post
prandial blood glucose should be less than 6.7 mmol/L. Blood sugar profile
should be checked before or after each meal; preprandial or postprandial
glucose level and the result should be less than 6 mmol/L or 6.7mmol/L,
respectively. Normal blood glucose level should be maintained with a mixture of
short and medium-acting insulin. Ultrasound scan that was done during the first
12 weeks of pregnancy provides accurate estimation of the period of gestation.
Meanwhile, scanning between 18– 20 weeks of gestation allows exclusion of any
major malformations and around 34 weeks of gestation, it permits assessment of
fetal growth. Regular assessment of fetal growth and wellbeing should be
performed.
C. Timing of Delivery
Delivery at up to 40
weeks of gestation is possible if the sugar control is good. But if there is
inadequate blood glucose control, or the presence of polyhydramnios, fetal
macrosomia or maternal obesity delivery at 38 weeks of gestation is indicated.
Delivery at earlier than 38 weeks is not really indicated to prevent
Respiratory Distress Syndrome in the premature baby.
Management of Labour
The intention is to achieve vaginal delivery.
Labour can be induced by doses of oxytocin. An artificial rupture of membrane
(ARM) should be performed. Blood glucose level needs to be monitored at
frequent intervals; mostly done at 2hourly. The fetus should be monitored
throughout labour and during vaginal delivery shoulder dystocia should be
anticipated. On the other hand, a caesarean section may be performed if there
is significant petal macrosomia or poor fetal status (CTG), or if labour fails
to progress satisfactorily. Uncomplicated diabetes not an indication for
operative delivery.
Follow Up of Women Who
Have Had Gestational Diabetes Mellitus
Follow up is important
as up to 50% of women with Gestational Diabetes Mellitus may develop overt
diabetes; mainly Type II. At the follow up visits, we should encourage her to
follow a diet which is appropriate for a diabetic. She should also be advised
to take these following measures;
1. Avoid becoming
obese
2. Take regular
exercises
3. Avoid cigarette
smoking
4. Checked annually
for hypertension
These women have a 50%
chance of developing Gestational Diabetes Mellitus in the future pregnancy. If
she intend to become pregnant again, testing for hyperglycaemia before
conception or in early pregnancy is recommended.
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